This disclosure relates to a die casting machine plunger and, more particularly, to a replaceable piston ring for the plunger.
A typical die casting machine includes a plunger that is axially moveable within a shot sleeve to force a shot of molten metal into a die. The plunger is moved in response to an actuator via a rod coupled to the plunger. The outer surface of the plunger is subject to wear as it rides along the inner diameter of the shot sleeve during harsh casting conditions. Typically, the plunger is of a one piece design, requiring the entire plunger to be replaced once worn.
Several multi-piece plungers have been proposed in which an outer piston ring is mounted onto a plunger body. In one example, the piston ring is constructed from a copper material that is replaceable. In the prior art configurations, a structure is secured to the plunger body to retain the piston ring. One end of the piston ring abuts a plunger wall, and the structure abuts the opposing end of the piston ring. In one arrangement, the structure is provided by the rod. In another arrangement, the structure is directly coupled to the rod.
Since the structure is loaded directly or indirectly by the rod, and the force on the rod varies throughout the casting operation, the ability of the structure to retain the piston ring on the plunger body may be compromised.